• Asian Journal of Atmospheric Environment
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• 제12권1호
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• pp.47-58
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• 2018

The aim of this work is to investigate the effect of atmospheric stability on near-field pollutant dispersion from rooftop emissions of a single cubic building using computational fluid dynamics (CFD). This paper used the shear stress transport (here after SST) k-${\omega}$ model for predicting the flow and pollutant dispersion around an isolated cubic building. CFD simulations were performed with two emission rates and six atmospheric stability conditions. The results of the simulations were compared with the data from wind tunnel experiments and the result of simulations obtained by previous studies in neutral atmospheric condition. The results indicate that the reattachment length on the roof ($X_R$) obtained by computations show good agreement with the experimental results. However, the reattachment length of the rooftop of the building ($X_F$) is greatly overestimated compared to the findings of wind tunnel test. The result also shows that the general distribution of dimensionless concentration given by SST k-${\omega}$ at the side and leeward wall surfaces is similar to that of the experiment. In unstable conditions, the length of the rooftop cavity was decreased. In stable conditions, the horizontal velocity in the lower part around the building was increased and the vertical velocity around the building was decreased. Stratification increased the horizontal cavity length and width near surface and unstable stratification decreased the horizontal cavity length and width near surface. Maintained stability increases the lateral spread of the plume on the leeward surface. The concentration levels close to the ground's surface under stable conditions were higher than under unstable and neutral conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.419-433
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• 2009

Pressure grouting is a common technique in geotechnical engineering to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressure grouting has been applied to a soil-nailing system which is widely used to improve slope stability. The soil-nailing design has been empirically performed in most geotechnical applications because the interaction between pressurized grouting paste and the adjacent ground mass is complicated and difficult to analyze. The purpose of this study is to analyze the increase of pullout resistance induced by pressurized grouting with the aid of performing laboratory model tests and field tests. In this paper, two main causes of pullout resistance increases induced by pressurized grouting were verified: the increase of residual stress; and the increase of coefficient of pullout friction. From the laboratory tests, it was found that residual stress in borehole increases by pressurized grouting and dilatancy angle could be estimated by cavity expansion theory using the measured wall displacements. From the field test results, the pullout resistance of soil-nailing with pressurized grouting was found to be 10% larger than that of soil-nailing with gravitational grouting, mainly caused by mean normal stress increase and dilatancy effect. So, the pullout resistance could be estimated by considering these two effects. The radial displacement increases with dilatancy angle increase and the dilatancy angle decreases with injection pressure increase. The measured pullout resistance obtained from field tests is in good agreement with the estimated one from the cavity expansion theory.

• Anatomy and Cell Biology
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• 제56권2호
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• pp.200-204
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• 2023

Although in counterpart, the sphenopalatine artery (SPA), has been well described in the medical literature, the sphenopalatine vein (SPV) has received scant attention. Therefore, the present anatomical study was performed. Additionally, we discuss the variations, embryology, and clinical significance of the SPV. Adult cadaveric specimens underwent dissection of the SPV. In addition, some specimens were submitted for histological analysis of this structure. The SPV was found to drain from the sphenoidal sinus and nasal septum. Small tributaries traveled through the nasal septum with the posterior septal branches of the SPA and nasopalatine nerve. The SPA and SPV were found to travel through the sphenopalatine foramen and another tributary was found to perforate the medial plate of the pterygoid process and to connect to the pterygoid venous plexus which traveled lateral to the medial plate of the pterygoid process. The vein traveled through the posterior part of the lateral wall of the nasal cavity with the posterior lateral nasal branches of the SPA and the lateral superior posterior nasal branches of the maxillary nerve. To our knowledge, this is the first anatomical study on the SPV in humans. Data on the SPV provides an improved anatomical understanding of the vascular network of the nasal cavity. Developing a more complete picture of the nasal cavity and its venous supply might help surgeons and clinicians better manage clinical entities such as posterior epistaxis, cavernous sinus infections, and perform endoscopic surgery with fewer complications.

• Tuberculosis and Respiratory Diseases
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• 제43권3호
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• pp.323-330
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• 1996

Objective : Cavitary lesion in pulmonary tuberculosis sometimes makes problems in the course of treatment. Especially, retreatment cases tend to respond poorly to current antituberculosis agents. So, authors tried to render a guideline for clinical approach toward cavitary lesions in pulmonary tuberculosis. Methods : Retrospective analysis of 33 pulmonary tuberculosis patients with cavitary lesions was made. All the patients had got treatment at National Masan Tuberculosis Hospital from Jan. 1995 to Aug. 1995. Results: The ratio between male and female was 10:1. Age distribution was 69.7% in 3rd and 4th decades. The locations of cavitary lesion were 60.6% in right upper lung field and 36.4% in left upper lung field. In the extent of disease, there were 12 cases(36.4%) in moderate advanced and 21 cases in far advanced. Cavitary lesions were closed in 5 eases and remained in 28 eases. In the cases of closed cavity, it was happened within $10.6{\pm}4.72$ months after they took treatment, the size of cavity was $35.5{\pm}17.1$ in long diameter, $27.0{\pm}12.2$ in short diameter and $4.6{\pm}2.1\;mm$ in wall thickness. In the cases of remained cavity, the size of cavity was $31.9{\pm}12.3$ in long diameter, $21.0{\pm}9.8$ in short diameter and $5.04{\pm}2.0\;mm$ in wall thickness. In terms of negative conversion, it took $3.8{\pm}2.17$ months in the case of closed cavity but it was happened within 5 months for only 4 patients in the case of remained cavity. In the point of past medication history, there was none in closed cavities but there were none in 1 case, once in 3 cases, two times in 9 cases and more than three times in 13 cases among remained cavitary lesions. Conclusion : In the retreatment cases of pulmonary tuberculosis with cavitary lesions, they tend to respond poorly to current antituberculosis agents. So, if the lesions are localized, operative intervention may be a proper method as adjunctive treatment.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제39권6호
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• pp.789-799
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• 2019

The settlement hardly occurs in structures supported by pile foundation such as abutment, culvert but a cavity is formed in the lower part of a structure. As a result, soil discharged from the lateral ground to the cavity accelerates the settlement of the lateral ground of the structure, resulting in a larger settlement. Therefore, in order to prevent problems caused by cavity under the structure supported by pile foundation, soil Flow Protector (briefly called 'FLP'), which can be easily installed on the side of structure, was developed. In this study, an laboratory model test was carried out to prove the reduction effect of settlement and to estimate the optimal installation length of the FLP. As a result, the installation of the FLP reduced the settlement of the lateral ground and prevented the leakage of lateral ground soil into the cavity. If the stiffness of the FLP is small, the state or active earth pressure is generated in the upper part, which is not favorable for stability. But if the stiffness of the FLP is high enough, the passive earth pressure area is generated in the upper part, which will be advantageous for the stability. Also, the increased installation length of FLP is effective to reduce the settlement. And the ratio of the optimal length of the FLP to the box structure height (H = 250 mm) are flexible FLP 1.38, stiff FLP 0.73.

• Journal of the korean academy of Pediatric Dentistry
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• 제27권4호
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• pp.517-523
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• 2000

Nasopharyngeal closure is a sphincter mechanism between the activities of the soft palate, lateral pharyngeal wall and the posterior pharyngeal wall, which divides the oral cavity and the nasal cavity. It participates in physiological activities such as swallowing, breathing and pronunciation. In case of an error in this mechanism, it is called a nasopharyngeal incompetence. The causes of this error are defects in (1) length, function, posture of the soft palate (2) depth and width of the nasopharynx, (3) activity of the posterior and lateral pharyngeal wall. The purpose of this study is to analyze the nasopharynx of cleft palate patients using lateral cephalograms and at the same time, evaluate the degree of hypernasality of each vowels to find its relationship with nasopharyngeal incompetence. The following results were obtained: 1. The length of the soft palate was markedly short than normal. 2. The adequate ratio was smaller than the normal value. 3. As the adequate ratio decreased, when articulating vowels, anatomic mVPI increased. 4. When articulating each vowels, anatomic VPI was in proportion with the degree of hypernasality. 5. The degree of hypernasality was greater in high vowels(/i/, /u/) than low vowel(/a/). From the above results, it can be concluded that in cleft palate patients, lateral cephalograms can be used effectively in diagnosing and evaluating nasopharyngeal incompetence. The anatomic structure of the nasopharynx has close relation to the degree of hypernasality.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제34권3호
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• pp.167-174
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• 2021

Recent investigation into the integrity of nuclear containment buildings has highlighted the importance of developing an elaborate diagnostic method to evaluate the distribution and size of cavities inside concrete walls. As part of developing such a method, this paper presents a finite element approach to modeling elastic waves propagating in the containment building walls of a nuclear power plant. We introduce a perfectly matched layer (PML) wave-absorbing boundary to limit the large-scale nuclear containment wall to the region of interest. The formulation results in a semi-discrete form with symmetric damping and stiffness matrices. The transient elastic wave equations for a mixed unsplit-field PML were solved for displacement and stresses in the time domain. Numerical results show that the sensitivity of displacement, velocity, acceleration, and stresses is large depending on the size and location of the cavity. The dynamic response of the wall slightly differs depending on the existence of the containment liner plate. The results of this study can be applied to a full-waveform inversion approach for characterizing cavities inside a containment wall.

• Journal of Institute of Control, Robotics and Systems
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• 제8권9호
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• pp.788-794
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• 2002

To improve surgical result of total hip arthroplasty (THA), there has been some approaches using a robotic milling system, which can make a precise cavity in the femur. Usually, to carve a femur, the surgical robot is controlled by a pre-programmed tool-path regardless of a surgeon's experience and Judgment. This paper presents a control method of a surgical robot for THA, which can be used as an advanced surgical tool. With a master/slave combined surgical robot, surgeon can directly control the motion and velocity of a surgical robot. The master/slave-combined robot is controlled to display a specific admittance for a surgeon's force to the surgical robot velocity. To prevent the over-carving of a femur, virtual hard wall is displayed on the surgical boundary. To evaluate the proposed control method of the master/slave-combined surgical robot, 2-DOF master/slave-combined manipulator is used in experiment.

• Journal of computational fluids engineering
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• 제15권1호
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• pp.1-8
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• 2010

RCCS is a passive safety-related system that removes the decay heat of VHTR when normal decay heat removal systems are in failure. Understanding thermo-hydraulics of RCCS is important to design a safer VHTR. RCCS consists of 292 cooling panels, which are placed in the reactor cavity. The layout of RCCS gives an idea that, for CFD simulations, cooling panels can be assumed to be one annulus tube. This assumption can reduce significantly the computational time, especially for the unsteady simulation. To simulate RCCS in an axisymmetric manner, three models were suggested and compared. Each model has (1) the same outer radius, (2) the same cross-sectional area (3) the same pressure drop, respectively, as the RCCS cooling panels. The steady-state simulation was conducted with these three models and the DO radiation model. It is found that over 90% of the heat from the outer wall of the reactor pressure vessel is transported to the RCCS by radiative heat transfer. The simulation with the third model, which has the same pressure drop as the design, estimates the closest wall temperature profiles to a thermo-hydraulic code, GAMMA+, result.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제21권2호
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• pp.329-340
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• 1997

A passive control of interaction of condensation shock wave / boundary layer for reducing the strength of condensation shock was conducted experimentally in a 2.5 * 8 cm$^{2}$ indraft type supersonic wind tunnel. The effects of following factors on passive control were investigated: 1) the thickness of porous wall, 2) the diameter of porous hole, and 3) the orientation of porous hole. On the other hand, the location of nonequilibrium condensation region and condensation shock wave was controlled by regulation of the stagnation conditions. Surface static pressure measurements as well as Schlieren observations of the flow field were obtained, and their effects were compared with the results the cases of without passive control. It was found that thinner porous wall, smaller porous hole and FFH orientation for the same cavity size and porosity of 12% are more favourable than the cases of its opposite.